Stretch Intensity vs. Inflammation: A Dose-dependent Association?

Abstract

The intensity of stretching is rarely reported in scientific literature. In this study, we examined the effects of stretching intensities at 30%, 60%, and 90% of maximum range of movement (mROM) on the inflammatory response of the right hamstring muscle. Methods: A randomised within-subject trial was conducted with 11 healthy recreationally active males over a three week period. Participants were strapped into an isokinetic dynamometer in the supine position, with the right knee fastened in a knee immobilizer. After randomising the ROM percentages, the hamstring muscle was moved to one of the three chosen ROM percentages for that week and held there for 5 x 60 seconds followed by a 10 second rest between repetitions. A 5ml blood sample was collected pre-, immediately post, and at 24 hours post intervention for high sensitivity C-reactive protein (hsCRP) assessments. Results: Significant increases in hsCRP levels were observed between 30% mROM and 90% mROM (p=0.004) and 60% mROM and 90% mROM (p=0.034), but not between 30% and 60% (p>0.05). Conclusions: Muscle stretching at submaximal levels does not elicit a significant systemic inflammatory responses

Respostas inflamatórias agudas ao treinamento de flexibilidade: uma revisão sistemática

“…In one of the quasi-experimental clinical trials, static flexibility training at different maximal ROM (30, 60 and 90%) in the right ischiotibial muscle promoted significant increases in hsCRP levels between 30 and 90% (p = 0.004) and 60 and 90% (p = 0.034), but not between 30 and 60% (p > 0.05), revealing that increases in the percentage of maximal ROM (intensity) are associated with a rise in hsCRP levels, causing possible systemic inflammation [21].…”

“…The evidence of three clinical trials with available data whose primary and secondary outcomes were the inflammatory effects caused by flexibility training at different intensities: one randomized clinical trial [20] and two quasi-experimental clinical trials [8,21].…”

“…In regard to the applicability and quality of the evidence, the studies included in the present review revealed high and critical risk of bias in assessment of the randomized clinical and quasi-experimental trials [8,20,21], respectively.…”

“…After the selection process, the following studies were included: one randomized clinical trial [20] and two quasi-experimental non-randomized studies [8,21].…”